Subsea Flowline Blockage Remediation Using Internal Heating Device

ABSTRACT

Coiled tubing may be placed inside a subsea flowline, such as with a subsea insertion tool, to remediate blockages in the flowline subsea. In embodiments, the subsea insertion tool is used to unspool a length of coiled tubing string from a coiled tubing reel and insert the unspooled coiled tubing string subsea into flowline to where a jetting nozzle is positioned proximate a blockage in flowline  120.  Fluid is provided, e.g. pumped, from chemical pumping unit  80  to coiled tubing string  100  through to jetting nozzle  110  to remediate the blockage in flowline  120.

RELATION TO OTHER APPLICATIONS

This application claims priority through U.S. Provisional Application 62/671,346 filed on May 14, 2018.

BACKGROUND

Currently, the task of inserting coiled tubing in a flowline involves retrieving the flowline to the surface such as onto a deck of a vessel and removing the flowline termination. Some tools exist that are used to push coiled tubing into a flowline but only topside. No tools accomplish remediation of a flowline blockage subsea using coiled tubing.

FIGURES

Various figures are included herein which illustrate aspects of embodiments of the disclosed inventions.

FIG. 1 is a view in partial perspective of an exemplary subsea insertion tool; and

FIG. 2 is a view in partial perspective of an exemplary subsea remediation system using the exemplary subsea insertion tool.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

In a first embodiment, referring generally to FIG. 1, subsea insertion tool 1 comprises coiled tubing inserter 10 adapted to insert and remove coiled tubing string 100 into the flowline 120 subsea; sealer 20 configured to form a dynamic seal on an outer diameter of coiled tubing string 100; one or more gate valves 30 adapted to aid in primary sealing of flowline line fluids from the environment; one or more disconnect valves 40 adapted to aid in emergency disconnection of coiled tubing string 100; large bore connector 15 adapted to aid in venting and/or flushing the flowline during operation to de-pressurize and de-inventory the flowline, where large bore means around 500 centimeters or more; and flowline connector 50 adapted to connect with a pipeline termination.

In embodiments, subsea coiled tubing inserter 10 is adapted to push and/or pull coiled tubing string 100 into and out from flowline 120 and may comprise coiled tubing injector head 103 (not specifically shown in the figures).

In embodiments, sealer 20 comprises a stripper packer.

In embodiments, disconnect valve 40 further comprises a blowout preventor valve, shear ram 41, grip/seal ram 42, or the like, or a combination thereof.

In embodiments, coiled tubing cutter 12 may also be present and used to cut coiled tubing string 100 in case of an emergency disconnect. Coiled tubing cutter 12 is typically located externally to coiled tubing inserter 10.

In certain embodiments, subsea insertion tool 1 may further comprise one or more flexible flowlines 122 (not specifically shown in the figures) disposed between subsea insertion tool 1 and flowline termination 123 (not specifically shown in the figures) which may be used for horizontal insertion to aid in alignment.

Subsea insertion tool 1 may also comprising an alignment system (not specifically shown in the figures) for aligning the tool with a pipeline termination.

In embodiments, subsea insertion tool 1 further comprises first remotely operated vehicle ROV panel 13, disposed proximate second end 1 a of the subsea insertion tool 1 and operatively in communication with coiled tubing inserter 10, and second remotely operated vehicle ROV panel 14, disposed proximate first end 1 a of subsea insertion tool 1 and operatively in communication with gate valve 30 and disconnect valve 40.

Referring now to FIG. 2, heated coiled tubing string system 2 comprises subsea insertion tool 1, which is as described above; one or more coiled tubing control units located topside on a vessel, each comprising coiled tubing reel 70; coiled tubing string 100 comprising a predetermined length of coiled tubing 102 disposed about coiled tubing reel 70; heater 101 disposed inside coiled tubing string 100; one or more jetting nozzles 110 disposed at a predetermined end of coiled tubing string 100; and vibrator 111 (not specifically shown in the figures) located at an end of coiled tubing string 100 where vibrator 111 is adapted to provide vibration to aid in horizontal movement within flowline 120

In typical embodiments, heater 101 comprises a heating cable such as a mineral insulated cable. Although illustrated as heating a discrete section of coiled tubing string 100 proximate a reel end of coiled tubing string 100, heater 101 may be configured to heat the entire length of coiled tubing string 100. Heater 101 is typically used to heat chemicals which are pumped down coiled tubing string 100 to a temperature required for remediation of the blockage.

Vibrator 111 may comprise an agitator, a vibrator, an impact hammer, or the like, or a combination thereof.

Mechanical tractor 112 (not specifically shown in the figures) may further be present and adapted to aid in horizontal movement within flowline 120. In such embodiments, mechanical tractor 112 would replace vibrator 111.

In contemplated embodiments, one or more mechanical scrapers/brushes 113 may be present and adapted to abrade a blockage 121 and remove it from flowline 120. In such embodiments, rotator 130 may be present and operatively in communication with mechanical scraper/brush 113 where rotator 130 is configured to rotate mechanical scraper/brush 113 to provide a rotational motion to help abrade the blockage and remove it from flowline 120.

In certain of these embodiments, chemical pumping unit 80 may also be present and in fluid communication with coiled tubing string 100.

In certain of these embodiments, subsea depressurizing and de-inventorying skid 200 may be present. If so, coiled tubing string 100 is typically disposed on an upper portion of subsea depressurizing and de-inventorying skid 200.

In the operation of exemplary methods, referring still to FIG. 2, coiled tubing may be used inside a subsea flowline to remediate blockages in the subsea flowline using heated coiled tubing string system 2, which is as described above. Coiled tubing string 100 typically comprises a predetermined length of coiled tubing disposed about coiled tubing reel 70.

Coiled tubing string 100 is typically unspooled from coiled tubing reel 70 and the unspooled coiled tubing string 100 inserted subsea into subsea flowline 120 to where jetting nozzle 110 is positioned proximate a blockage in flowline 120. Fluid is provided, e.g. pumped, from chemical pumping unit 80 to coiled tubing string 100 through to jetting nozzle 110 to remediate the blockage in flowline 120.

In certain embodiments, heater 101 is energized to heat fluid within coiled tubing string 100 to a temperature appropriate the achieve the remediation of the blockage.

Coiled tubing string 100 may be inserted subsea into the subsea flowline from a pipeline termination such as pipeline end terminations (PLET), flowline terminators (FLET), pipeline end manifolds (PLEM), or the like, from platform at a riser, or the like. In other embodiments, coiled tubing string 100 is inserted subsea into flowline 120 using subsea insertion tool 1 deployed subsea, where subsea insertion tool 1 is as described above. If present, gate valve 30 may be used when coiled tubing string 100 is not in a bore of a valve.

In embodiments where subsea coiled tubing inserter 10 comprises coiled tubing injector head 103, subsea coiled tubing inserter 10 may be used to selectively insert coiled tubing string 100 into and remove coiled tubing string 100 out from flowline 120.

In embodiments using subsea insertion tool 1, disconnect valve 40 may be used for emergency disconnection of coiled tubing string 100. Further, large bore connector 15 may be used to vent/flush flowline 120 and subsea insertion tool 1 during operation to de-pressurize and de-inventory flowline 120. Further still, flowline connector 50 may be used to connect with a pipeline termination. In these embodiments, sealer 20 may be used to form a dynamic seal on an outer diameter of coiled tubing string 100.

Where subsea insertion tool 1 further comprises coiled tubing cutter 12 located externally to coiled tubing inserter 10, coiled tubing cutter 12 may be used to cut coiled tubing string 100 in case of emergency disconnect.

Where subsea insertion tool 1 further comprises flexible flowline 122, flexible flowline 122 may be used during horizontal insertion of coiled tubing string 100 to aid in alignment of the bore of subsea insertion tool 1 with the bore of flowline 120. Similarly, where subsea insertion tool 1 further comprises an alignment system, the alignment system may be to aid in aligning subsea insertion tool 1 with a pipeline termination.

In embodiments, subsea insertion tool 1 may be positioned in a substantially horizontal position, as illustrated in FIG. 2, or a substantially vertical position relative to a seabed. In addition, subsea insertion tool 1 may be positioned or otherwise placed onto mudmat 60.

In embodiments, subsea insertion tool 1 may further comprise a balance structure for use in vertical position configurations and the balance structure used to transmit loads from subsea insertion tool 1 to a seabed and to provide a foundation for subsea insertion tool 1.

The foregoing disclosure and description of the inventions are illustrative and explanatory. Various changes in the size, shape, and materials, as well as in the details of the illustrative construction and/or an illustrative method may be made without departing from the spirit of the invention. 

1. A subsea insertion tool, comprising: a. a coiled tubing inserter adapted to insert a coiled tubing string into, and remove the coiled tubing string out from, a flowline subsea; b. a sealer configured to form a dynamic seal on an outer diameter of the coiled tubing string; c. a gate valve adapted to aid in primary sealing of flowline line fluids from the environment; d. a disconnect valve adapted to aid in emergency disconnection of the coiled tubing string; e. a large bore connector adapted to aid in venting and/or flushing the flowline during operation to de-pressurize and de-inventory the flowline; and f. a flowline connector adapted to connect with a pipeline termination.
 2. The subsea insertion tool of claim 1 wherein the subsea coiled tubing inserter comprises a coiled tubing injector head.
 3. The subsea insertion tool of claim 1 wherein the sealer comprises a stripper packer.
 4. The subsea insertion tool of claim 1 wherein the disconnect valve further comprises a blowout preventor valve.
 5. The subsea insertion tool of claim 1 wherein the disconnect valve further comprises a shear ram or a grip/seal ram.
 6. The subsea insertion tool of claim 1, further comprising a coiled tubing cutter adapted to cut coiled tubing and/or the coiled tubing string in case of emergency disconnect, the coiled tubing cutter located externally to the coiled tubing inserter.
 7. The subsea insertion tool of claim 1, further comprising a flexible flowline disposed between the subsea insertion tool and the flowline termination and adapted to aid with horizontal insertion to aid in alignment.
 8. The subsea insertion tool of claim 1, further comprising an alignment system for aligning the tool with a pipeline termination.
 9. The subsea insertion tool of claim 1, further comprising: a. a first remotely operated vehicle (ROV) panel disposed proximate a first end of the subsea insertion tool and operatively in communication with the coiled tubing inserter; and b. a second remotely operated vehicle (ROV) panel disposed proximate a second end of the subsea insertion tool and operatively in communication with the gate valve and the disconnect valve.
 10. A coiled tubing string assembly, comprising: a. a coiled tubing control unit located on a topside vessel, the coiled tubing control unit comprising a coiled tubing reel; b. a coiled tubing string comprising a predetermined length of coiled tubing disposed about the coiled tubing reel; c. a heater disposed inside the coiled tubing; d. a jetting nozzle disposed at a predetermined end of the coiled tubing string; and e. a vibrator at the end of the coiled tubing string, the vibrator adapted to provide vibration to aid in horizontal movement within a flowline.
 11. The coiled tubing string assembly of claim 10, wherein the heater comprises a heating cable.
 12. The coiled tubing string assembly of claim 11, wherein the heating cable comprises a mineral insulated cable.
 13. The coiled tubing string assembly of claim 10, wherein the vibrator comprises an agitator, a vibrator, or an impact hammer.
 14. A heated coiled tubing string system, comprising a coiled tubing string assembly, the coiled tubing string assembly comprising: a. a coiled tubing control unit comprising a coiled tubing reel; b. a coiled tubing string comprising a predetermined length of coiled tubing disposed about the coiled tubing reel; c. a heater disposed inside the coiled tubing; and d. a jetting nozzle disposed at a predetermined end of the coiled tubing string.
 15. A method of using coiled tubing inside a subsea flowline to remediate blockages in a subsea flowline using a heated coiled tubing string system which comprises a coiled tubing string assembly, the coiled tubing string assembly comprising a coiled tubing control unit comprising a coiled tubing reel; a coiled tubing string comprising a predetermined length of coiled tubing disposed about the coiled tubing reel; a heater disposed inside the coiled tubing; and a jetting nozzle disposed at a predetermined end of the coiled tubing string, the heated coiled tubing string system further comprising a chemical pumping unit in fluid communication with the coiled tubing string, the method comprising: a. unspooling the coiled tubing string from the coiled tubing reel; b. inserting the unspooled coiled tubing string subsea into a flowline subsea until the jetting nozzle is positioned proximate a blockage; c. providing fluid from the chemical pumping unit to the coiled tubing string through to the jetting nozzle; and d. using the jetting nozzle to remediate the blockage in the subsea flowline.
 16. The method of claim 15, wherein the coiled tubing string is inserted subsea into the subsea flowline from a pipeline termination.
 17. The method of claim 15, wherein the coiled tubing string is inserted subsea into the subsea flowline from a platform at a riser.
 18. The method of claim 15, further comprising energizing the heater to heat fluid within the coiled tubing string to a temperature appropriate the achieve the remediation of the blockage.
 19. The method of claim 15, wherein the coiled tubing string is inserted subsea into the subsea flowline using a subsea insertion tool deployed subsea, the subsea insertion tool comprising a coiled tubing inserter adapted to insert and remove the coiled tubing string into the flowline subsea; a sealer configured to form a dynamic seal on an outer diameter of the coiled tubing string; a gate valve adapted to aid in primary sealing of flowline line fluids from the environment; a disconnect valve adapted to aid in emergency disconnection of the coiled tubing string; a large bore connector adapted to aid in venting and/or flushing the flowline during operation to de-pressurize and de-inventory the flowline; and a flowline connector adapted to connect with a pipeline termination.
 20. The method of claim 19, wherein the gate valve is used when the coiled tubing is not in a bore of the valve. 